Effects of Inoculation with Stress-Tolerant Rhizobia on the Response of Alfalfa (Medicago sativa L.) to Combined Salinity and Cadmium Stress.

Agricultural soil salinization, which is often combined with heavy-metal contamination, is an ever-growing problem in the current era of global change. Legumes have a high potential for nitrogen fixation and are ideal crops for the reclamation of degraded soils. Alfalfa (Medicago sativa) is a valuable forage crop cultivated worldwide. Alfalfa plants fertilized with nitrogen or inoculated with a salt- and cadmium-tolerant Sinorhizobium meliloti strain were subjected to combined NaCl and CdCl2 stresses. Our results showed that inoculated plants presented higher aerial biomass than nitrogen-fertilized plants when they were exposed to salinity and cadmium together. To assess the mechanisms involved in the plant response to the combined stresses, superoxide dismutase and catalase antioxidant enzymatic activities were determined. Both increased upon stress; however, the increase in catalase activity was significantly less marked for inoculated plants, suggesting that other tolerance mechanisms might be active. Cd accumulation was lower in inoculated plants than in fertilized plants, which appears to imply that inoculation somehow prevented cadmium uptake by the plant roots. Expression analyses of several involved genes suggested that inoculation stimulated the biosynthesis of proline, phytochelatins, and homophytochelatins, together indicating that inoculated plants might be better suited to withstand combined salinity and cadmium stress effects.

Tuning the Size of Palladium Nanoparticles in Organic and Aqueous Solutions: Influence of Aminated and Thiolated Ligands.

Highly monodispersed palladium nanoparticles have been synthesized by a two-phase reduction method using two different capping agents, alkylamines and alkanethiols. The influence of ligand type in the properties of palladium nanoparticles have been analyzed in detail by means of several techniques as Infrared and Ultraviolet-Visible Spectroscopy, X-ray Diffraction and Transmission Electron Microscopy. It is shown how the size can be tuned easily between 2 and 4 nm by using alkylamines ligands with carbon chains of different lengths, while keeping up high purity and crystallinity. The transfer of these nanoparticles to water phase has been achieved by the ligand exchange process. In contrast, when alkanethiols are used as stabilizers no correlation between carbon chain length and size has been observed. This distinct chemical reactivity between palladium and mentioned ligands produces some particular electronic and magnetic properties that are analyzed by Electron Magnetic Resonance. The presence of free radicals associated with palladium and capping agent bond has been confirmed. No evidences of ferromagnetic behavior coming from Palladium nanoparticles have been found out in any of the studied samples.

Specific absorption rate of magnetite nanoparticle powders with and without surrounding organic ligands.

Magnetite nanoparticles have been synthesized at different temperatures in order to get nanoparticles of different average sizes. Powders of the synthesized nanoparticles were introduced in a radio frequency electromagnetic apparatus built to perform hyperthermia measurements in laboratory animals. The nanoparticles synthesized at 80 degrees C, the ones giving the largest specific absorption rate values, have been functionalized with different organic ligands to study the influence of functionalization on specific absorption rate values. In all the synthesized nanoparticles, with and without organic surroundings, specific absorption rate measurements have been performed to study the influence of applied magnetic field intensity an frequency.

Functionalized Fe3O4@Au superparamagnetic nanoparticles: in vitro bioactivity.

The interaction of nanoparticles with cells has been a focus of interest during the past decade. We report the fabrication and characterization of hydrosoluble Fe3O4@Au nanoparticles functionalized with biocompatible and fluorescent molecules and their interaction with cell cultures by visualizing them with confocal microscopy. Gold covered iron oxide nanoparticles were synthesized by reducing metal salts in the presence of oleylamine and oleic acid. The functionalization of these particles with an amphiphilic polymer provides a water soluble corona as well as the possibility to incorporate different molecules relevant for bio-applications such as poly(ethylene glycol), glucose or a cadaverine derived dye. The particle size, and the presence of polymer layers and conjugated molecules were characterized and confirmed by transmission electron microscopy, thermogravimetric measurements and infrared spectroscopy. A complete magnetic study was performed, showing that gold provides an optimum coating, which enhances the superparamagnetic behaviour observed above 10-15 K in this kind of nanoparticle. The interaction with cells and the cytotoxicity of the Fe3O4@Au preparations were determined upon incubation with the HeLa cell line. These nanoparticles showed no cytotoxicity when evaluated by the MTT assay and it was demonstrated that nanoparticles clearly interacted with the cells, showing a higher level of accumulation in the cells for glucose conjugated nanoparticles.

[Atypical radiologic manifestations of Pneumocystis carinii pneumonia]. / Manifestaciones radiológicas atípicas de la neumonía por Pneumocystis carinii.

Pneumonia due to Pneumocystis carinii (PC) is characterized, in most cases, by the existence of infiltrates of interstitium or bilateral interstitium-alveolar type on the thorax radiography. However atypical radiological findings associated with this type of opportunistic infection are being described more and more frequently. We present two patients with Acquire Immune Deficiency Syndrome (AIDS) and pulmonary infection due to PC, with very unusual radiological findings. First patient showed multiple pulmonary cavitated nodules; the other a cavitated infiltrate in superior right lobule. Clinicians dealing with AIDS patients must be familiar with this unusual radiologic findings associated with PC in order to avoid diagnostic mistakes.